Industrial requirements for tough plastic sheeting is accelerating because of the need to replace high energy metals and reduce the weight in fabricated products for appliances, automotive and building construction.
Filled materials have been developed for increased toughness and modulus, however, such approaches increase weight and costs because of compounding problems or brittleness requiring high cost plasticizers.
It has been found that particular composite sheet members having a plurality of coextruded laminar layers provide unexpectedly superior toughness yet are economically produced and fabricated.
Coextrusion of layered materials have been carried out in pipe fabrication wherein a foamed core material has been coextruded between skins of solid wall material to reduce weight. Various sheets or films have been coextruded to produce barrier or heat sealing skins. Hence, coextrusion processes are known and coextrusion equipment is commercially available.
Hence, the object of the present invention is to prepare coextruded laminar sheet members that can be formed for appliances or automotive parts wherein the laminar layers are particular layers that in combination provide unexpectedly tough sheet members with a superior combination of properties.
In particular, it has been found that composite sheet members having a plurality of coextruded laminar layers prepared from polyblends can be varied in toughness depending upon the amount and kinds of grafted rubber dispersed in the base and external layers along with the geometry of said layers.